1. Field of the Invention
The present invention relates to a composition for cleaning and etching electronic display devices and substrates, and more particularly to a composition for etching Si, SiO.sub.2, SiN.sub.X, and metallic thin layers while also removing contaminants formed on the surfaces of the etching layers during the manufacturing process of electronic display devices, quartz devices, and semiconductor substrates.
2. Description of the Prior Art
In general, the manufacture of electronic display devices and substrates commonly involves cleaning and etching steps. For example, in the manufacture of Cathode Ray Tube (CRT), a multi-step cleaning is implemented. Prior to coating process, CRT bulb is subjected to a cleaning process which involves 10.about.18% hydrofluoric Acid (HF) solution. Then, the steps of inner panel black coating, screen coating, lacquer coating, aluminizing, funnel inner graphite coating, panel/funnel frit sealing, neck washing, mounting and exhausting, funnel outer graphite coating, and panel face coating are performed. For the panel face coating, the coating materials may include In.sub.2 O.sub.3, Sb.sub.2 O.sub.3, and SiO.sub.2, and prior to face coating, the surface contaminants are removed by cleaning with 1.about.2% HF or hydrogen ammonium fluoride (or ammonium bifluoride) solution. For defective coating layers, a 10.about.30% ammonium bifluoride solution is used (before sintering process) and polishing with CeO.sub.2 is required (after backing).
In the manufacture of another electronic display device LCD, the manufacturing process may include cleaning and etching during lithography. Here, in the surfaces of a large substrates, it is important to etch uniformly to obtain a high degree of accuracy.
The table below shows compositions for cleaning and etching solutions commonly used and the types of materials to be cleaned and etched for LCD and semiconductor wafer.
For cleaning SiO.sub.2 1. H.sub.2 SO.sub.4 :H.sub.2 O.sub.2 (6:1), 120.degree. C. 2. 50% HF:H.sub.2 O (1:100.about.1000) 3. NH.sub.4 OH:H.sub.2 O.sub.2 :H.sub.2 O (1:1:7) SC-1 4. Hcl:H.sub.2 O.sub.2 :H.sub.2 O (1:1:6) SC-2 5. D.I.W. (deionized water) rinse For etching SiO.sub.2 layer 1. 40% NH4F:50% HF (7:1) BOE 2. 40% NH4F:50% HF (7:1) +H.sub.2 O.sub.2 For etching SiN.sub.x layer H.sub.3 PO.sub.4 :H.sub.2 O (85:1) or 40% NH.sub.4 F:50% HF (20:1) For etching Al and its alloy layer H.sub.3 PO.sub.4 :CH.sub.3 COOH:HNO.sub.3 :H.sub.2 O (65:5:5:25)
The required conditions of above cleaning and etching solutions may include control of cleaning and etching rate, etching selectivity for upper and lower layers, control of etching profile, control of etching within the multi-layers, stability and homogeneity of the solutions, and reproducibility of etching process.
For quartz devices which are used for manufacturing of wafer, the manufacturing process is outlined as follows:
Raw material-cleaning (11.about.16.5% HF solution, 2.about.3 minutes)--waxing--cutting and polishing--dewaxing--ultrasonic washing--cleaning (15% HF solution, 5 minutes)--benching--cleaning (11.about.16.5% HF solution, 5 minutes)--drying--heating (1200.degree. C.)--cleaning (11.about.16.5% HF solution, 5 minutes)--drying.
Here, a high concentration of HF solution are used for removing the surface contaminants and thermally oxidized layer formed during the above process, but HF solution may cause problems relating to smoothness, etching damage, crack, etc. The quartz devices thus obtained are then used for depositing layers and further heat-treating a wafer, and the contaminants formed during the latter processes are also cleaned by the utilization of HF solution at 2.about.25% concentration.
The following outline describes the fabrication process of semiconductor wafers: